Tweezing of Magnetic and Non‐Magnetic Objects with Magnetic Fields

Abstract

Although strong magnetic fields cannot be conveniently "focused" like light, modern microfabrication techniques enable preparation of microstructures with which the field gradients - and resulting magnetic forces - can be localized to very small dimensions. This ability provides the foundation for magnetic tweezers which in their classical variant can address magnetic targets. More recently, the so-called negative magnetophoretic tweezers have also been developed which enable trapping and manipulations of completely nonmagnetic particles provided that they are suspended in a high-magnetic-susceptibility liquid. These two modes of magnetic tweezing are complimentary techniques tailorable for different types of applications. This Progress Report provides the theoretical basis for both modalities and illustrates their specific uses ranging from the manipulation of colloids in 2D and 3D, to trapping of living cells, control of cell function, experiments with single molecules, and more.

Force-Mediating Magnetic Nanoparticles to Engineer Neuronal Cell Function

“…The dimensions of the channel and micropipette are the determining factor for precision. Alternatively, optical, magnetic, thermal, or electric tweezers are tools that allow for direct force manipulation depending on the physical properties of the force-mediating object (Thoumine et al, 2000 ; Baumgartner et al, 2003 ; Jeney et al, 2004 ; Neuman and Nagy, 2008 ; Kilinc et al, 2015 ; Allen Liu, 2016 ; Tay et al, 2016b ; Timonen and Grzybowski, 2017 ). An external magnetic, optical, or electrical field is required to direct and accelerate the internalized object (Figure 2A ).…”

Mechanical Characterization for Cellular Mechanobiology: Current Trends and Future Prospects

“…Advantages of MT include its cost-effectiveness and ease of implementation, superior to other single-molecule techniques (Kemmerich et al, 2016). Furthermore, MTs can generate forces inside closed opaque bodies, such as living cells, which is not the case with other non-invasive methods (Timonen and Grzybowski, 2017). MTs have been used extensively to generate tension on cell adhesion molecules, and then observing the cellular response to reveal mechanotransduction pathways (Guilluy et al, 2014;Marjoram et al, 2016).…”

Multifarious Transit Gates for Programmable Delivery of Bio‐functionalized Matters

“…Recently, magnetic tweezers and micromagnetophoretic patterns offer significant advancements by overcoming the abovementioned complications toward precise particle, droplet, and cell manipulations. Furthermore, we have demonstrated a class of integrated circuits of micromagnetophoretic patterns, such as conductors, diodes, capacitors, and transistors to execute sequential and parallel operations on an ensemble of single particles and cells .…”

“…However, none of these approaches have demonstrated the simultaneous programmable manipulation of individual objects for massive arrays without any damage to biomolecules. Recently, magnetic tweezers [6,12,13] and micromagnetophoretic patterns [14][15][16][17][18][19][20][21][22][23][24][25] offer significant advancements by overcoming the abovementioned complications toward precise particle, droplet, and cell manipulations. Furthermore, we have demonstrated a class of integrated circuits of micromagnetophoretic patterns, such as conductors, diodes, capacitors, and transistors to execute sequential and parallel operations on an ensemble of single particles and cells.…”